1. Field of the Invention
The present disclosure relates generally to evaluating the integrity of structures installed in a wellbore, e.g., casing, liners and production tubing deployed in a hydrocarbon recovery wellbore. More particularly, embodiments of the disclosure relate to methods of hardness testing of metallic components subsequent to installing the metallic components in the wellbore.
2. Background
In the field of well construction in the oil at d gas industry, there has been occasion when one grade of the tubulars (casing, liner or completion tubing) has been mistaken for a different grade of tubular. This can occur through an error in material delivery from the vendor, poor casing design, lack of quality assurance/control (QA/QC) or a combination of all three. When wellbore conditions call for a particular grade of tubular, die result of installing a misidentified tubular can be that the weight or grade of steel being used is inadequate, or suspect at the very least. This may lead to a compromise in integrity of the tubular or premature failure during the lifecycle of the wellbore, particularly when the tubulars are installed in high-temperature-high-pressure (HTHP) wellbores and/or high hydrogen sulfide (H2S) or carbon dioxide (CO2) environments.
Often, tubulars are marked with color-coded bands, as set forth in API Spec 5CT, Section 11, marking, as an industry standard at one end that are intended to identify the grade of the tubulars and threaded connections or couplings. However, once the tubulars are installed in a wellbore, the color coded bands may not be visible, and the only recourse for determining the strength of the installed tubulars is to refer to the Mill Certificate. The Mill Certificate is a steel industry document that accompanies the shipments of tubulars when they depart the mill, and identify the tubulars by the manufacturing standards under which the tubulars were manufactured. Since the Mill Certificate may be separated from the tubulars before installation in the wellbore, or since the Mill Certificate may be inaccurate, reliance on the Mill Certificate is prone to error and is not a fail-safe method of establishing exactly what grade of tubulars are installed in the well. A need exists for devices and methods to test the hardness of the steel at any given point in the well while the pipe is in situ. The need exists, not necessarily for any specific well condition, rather in the event of a tubular failure, for assessing the failure mechanisms and for determining the appropriate hardness of down-hole steel structures. There may be both mechanical and geological reasons for assessing the hardness of down-hole steel structures, so a need exists for analysis tools for this type of analysis.